Ferritic Stainless Steels

AMBICA STEELS PRODUCED VARIOUS STAINLESS STEEL PRODUCTS OF DIFFERENT GRADES, FERRITIC STAINLESS STEEL IS ONE OF THEM i.e AISI 400 SERIES GRADE.

Ferritic stainless steels are generally classified in the 400 series.These are nickel-free stainless steels which contain varying chromium content of 12- 18%, but a lower carbon content than the martensitic. A special heat resistant ferritic grade contains 26% Cr.The most common specifications are 430, 409 and weldable 12% Cr steels.

They are usually chosen for their excellent corrosion resistance and oxidation resistance at elevated temperature.Having greater strength than carbon steels, ferritic steels provide an advantage in many applications where thinner materials and reduced weight are necessary, such as automotive emission control systems. They are always magnetic and non hardenable by heat treating.

After certain high temperature exposures, the unstabilized ferritic grades can be susceptible to intergranular corrosion, including welding. A post-weld heat treatment and a stabilized grade is recommended for applications that require welding.
The commonly used grades are 409,430 etc.

Formability

Ferritic stainless steels exhibits low formability.

Weldability

Some restrictions are imposed on welding due to the metallurgical structure of the ferritic grades. In the heat affected zone, the unstabilized ferritic grades can form martensite leading to a loss of ductility. The grades which are stabilized with titanium or niobium have improved ductility in the as-welded condition.Poor weldability generally limits their applications as welded components to thin gauge material. Welded joints can exhibit low ductility and toughness due to grain growth, especially in heavy sections. Post-weld heat treatments will generally improve the ductility of weld zones.